Texas Instruments CY74FCT240CTSOCT

Overview

CY74FCT240CTSOCT from Texas Instruments is an octal 3-state noninverting buffer/line driver IC used for memory address driving, clock distribution, and bus transceiver applications. It features 64-mA sink / 32-mA source output drive, 4.3-ns maximum propagation delay (tPLH/tPHL), Ioff partial-power-down support, and TTL-compatible input/output logic levels.

For engineers reviewing the CY74FCT240CTSOCT datasheet, CY74FCT240CTSOCT pinout, CY74FCT240CTSOCT application, or CY74FCT240CTSOCT equivalent, key selection criteria include 3-state bus isolation capability, industrial temperature range (–40°C to 85°C), SOIC-20 package thermal performance (θJA = 58°C/W), and compatibility with legacy FCT/F logic families.

Technical Context

The CY74FCT240CTSOCT implements dual 4-bit noninverting buffers with independent 3-state enable controls (OEA, OEB), each driving four outputs (OA0–OA3, OB0–OB3) from corresponding inputs (DA0–DA3, DB0–DB3). Its edge-rate control circuitry reduces switching noise while maintaining matched rise/fall times.

It supports partial-power-down via Ioff, which disables outputs and limits reverse current when VCC = 0 V. Input thresholds (VIH = 2 V min, VIL = 0.8 V max) and output voltage levels (VOH = 2.4 V min at –32 mA, VOL = 0.55 V max at 64 mA) ensure direct interfacing with TTL, NMOS, and CMOS logic without level-shifting components.

Key Specifications

Pinout & Package

Package: SOIC-20 (DW), 7.5 mm × 12.8 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1 (unlimited reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state buffer applications.

Compared with SN74FCT240CTSOCT, CY74FCT240CTSOCT offers identical functionality and drop-in compatibility; versus 74ACT240SCX, it provides essential Ioff protection and lower static current but requires tighter VCC regulation.

Availability

CY74FCT240CTSOCT is available at Aetrix Electronics and suitable for industrial automation, telecommunications infrastructure, and legacy system upgrades requiring stable component supply, long-lifecycle support, and RoHS-compliant SOIC packaging.

Supply support for CY74FCT240CTSOCT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions with over 50 years of industrial-grade product development.

The CY74FCT240CTSOCT belongs to TI's FCT logic family, engineered for high-speed, low-noise 5-V bus interfacing in mission-critical industrial and communications systems where reliability and compatibility with legacy TTL infrastructure are essential.

FAQ

What is the maximum operating frequency supported by the CY74FCT240CTSOCT?

The CY74FCT240CTSOCT does not specify a maximum clock frequency, but its 4.3-ns propagation delay and 5-ns enable/disable times support reliable operation in systems with bus frequencies up to 25 MHz when driving ≤50-pF loads. For higher frequencies, signal integrity depends on PCB layout, termination, and load capacitance - always verify timing margins using the device's actual tPLH/tPHL and tPZL/tPHZ values under your specific conditions. The CY74FCT240CTSOCT is optimized for burst-mode or asynchronous bus applications rather than continuous high-frequency clock distribution.

Does the CY74FCT240CTSOCT support hot-swap operation?

Yes, the CY74FCT240CTSOCT supports hot-swap operation through its Ioff feature: when VCC = 0 V, the outputs are disabled and leakage remains ≤±1 µA even with input/output voltages up to 4.5 V. This prevents damaging current backflow during live insertion or removal in backplane or modular systems. However, proper sequencing of enable signals (OEA/OEB held inactive until VCC stabilizes) and use of series resistors on inputs/outputs are recommended per TI application notes to ensure robust hot-swap behavior. The CY74FCT240CTSOCT is commonly deployed in industrial PLC carrier boards for this purpose.

Can the CY74FCT240CTSOCT interface directly with 3.3-V logic devices?

The CY74FCT240CTSOCT accepts 3.3-V logic-high inputs reliably (VIH min = 2.0 V), but its outputs swing to ~3.3 V (VOH typ = 3.3 V at –32 mA) - sufficient to drive most 3.3-V CMOS inputs (VIH ≥ 2.0 V). However, it is not 3.3-V tolerant on outputs: driving a 3.3-V device with VCC = 5 V may exceed that device's absolute maximum input voltage. For bidirectional 3.3-V/5-V interfacing, use dedicated level translators. The CY74FCT240CTSOCT is best suited for unidirectional 5-V bus extension where downstream devices tolerate 5-V inputs or have 5-V-tolerant I/O.

What is the thermal resistance (θJA) of the CY74FCT240CTSOCT in SOIC package?

The CY74FCT240CTSOCT in SOIC-20 (DW) package has a specified junction-to-ambient thermal resistance (θJA) of 58°C/W under standard JEDEC test conditions (1-layer 1-oz copper, 1-in² pad). Actual θJA in end equipment will vary based on PCB copper area, airflow, and nearby heat sources. For continuous 64-mA sink operation across all eight outputs, power dissipation can reach ~180 mW - resulting in ~10.4°C junction-to-ambient rise above ambient. TI recommends verifying thermal performance with IR imaging or thermocouple measurement in the final layout. The CY74FCT240CTSOCT's rated operating range (–40°C to +85°C) assumes proper thermal design.

How does the CY74FCT240CTSOCT differ from the CY74FCT240ATSOCT?

The CY74FCT240CTSOCT and CY74FCT240ATSOCT share identical pinout, package, and logic function, but differ in propagation delay: the 'C' version has 4.3-ns max tPLH/tPHL, while the 'A' version is 4.8 ns. Both operate over –40°C to +85°C and use the same VCC range (4.75–5.25 V). The 'C' grade is selected for timing-critical applications such as high-speed memory addressing or low-latency control loops where sub-500-ps timing margin improvements matter. The CY74FCT240CTSOCT also uses the same FCT240C top-side marking and tape-and-reel packaging (2000 pcs/reel) as documented in TI's ordering table.